Exothermic mtxtuke



Patented Dec. 19, 1939 UNITED s'rarss PATENT QFFICE EXOTHERRIIO MIXTUREtion of Missouri No Drawing. Application December 4, 1936,

' Serial No. 114,204

16 Claims.

This invention relates to an exothermic chemical composition which, whenmoistened with water, or aqueous liquid, spontaneously evolves acontrollable quantity of heat and may be used in pads or envelopes ofsuitable construction for various purposes, such as thrrapeutic heatingpads, hair-waving heating pads, and the like.

The heat evolving properties of the chemical composition depend upon theprinciple of oxidation-reduction which is known to be a highlyexothermic chemical process, and which is set in action by themoistening of the chemical composition with the liquid. Under certainoperating conditions it is essential that the reactions conform closelyto well defined requirements in order that best results be secured. Forexample, in a hair waving pad when the mixture is moistened theresulting temperature should rise to the boiling point of the liquid infrom thirty seconds to three minutes, and this temperature should besustained for about five minutes and then increased about 2 to 10 C. inone to three minutes, and thereafter drop quite rapidly to about 50 C.when the pad may be handled by the operator without discomfort.

It is necessary that the water vapor evolved during the active heatingperiod of the composi tion be emitted slowly and gently to avoid burningthe scalp by strong jets of steam. It is also necessary that thecomposition be of a stable character. so that pads several months oldwill 'commence heating within two or three minutes after moistening.

The objects of the invention are to fulfill the above mentionedrequirements and to avoid the disadvantages expressed or implied.

The composition consists primarily of a mixture of metals with otheringredients which in the presence of water aid in the oxidation of themetallic mixture. Aluminum is to be preferred as the principal metallicingredient because of its cheapness, convenience, and the high heat offormation of its compounds'although iron, magnesium, zinc, cadmium andother metals may be used. In practice it is found that the compositionis improved by the use of a secondary metal, positioned lower in theelectromotive series of metals, such as copper, zinc, tin,bismuth,'antimony, lead, mercury, arsenic, and active alloys of the samecontaining sufllcient of the named metal to be substantially as activeas the named metal. The purpose of these metals is to supply heat bymeans of their oxidation. We have found that the duration the heatingperiod may be (Cl. HF-3) oxidizingdecomposition products which areformed when it is acidified, potassium chlorate is one of the mostconvenient oxidizing agents to use.

We find that the proportion of this ingredient has a pronounced eiIectupon the course of the heating period. particularly in determining thepoint oi rise above the boiling temperature of water and the rate offinal cooling.

An acidic substance which produces an d by hydrolysis, and whichcontains a metal chplaceable by the principal metal reducing agent,serves not only to act as a source of acid to decompose the oxidizingagent but also to supply quickly available heat by means of adisplacement reaction. The proportion and properties of this ingredientregulates the time necessary to reach the boiling temperature of water.This substance may be cupric sulfate, cupric nitrate, cuprous chloride,cupric iormate, cupric tartr'ate, cupric chlorate, cupric lactate,eupricsalicylate, cupric sulflte. cupric-phosphate, cupric acetate,cuprous bromide, cuprous sulilte, cuprous iodide, cuprous ammoniumiodide, and the corresponding salts of iron, cobalt, nickel, tin,bismuth, mercury, arsenic, antimony, and lead. However, it is foundthat85 greater stability of the composition will result if the salts ofrelatively low solubility such as cuprous chloride and cupric tartratoare selected.

In place of the above named source of an acidic media which produces apreponderance of hydrow gen ions, certain soluble solid organic acidsmay be used and their very slight tendency to absorb water from theatmospil -.."e helps minimize undesirable decomposition of theingredients due to the absorption of moisture from the atmosphere. 5

Another advantage of the weak solid organic acids is that their partialwetting by means of small amounts of water in the surrounding atmospherehas less corrosive and deleterious eflectn on the other ingredients,whereas the hydrolysis of acidic inorganic salts like cuprous chloridemay result in the formation of strong mineral acids which attack otheractive insrodients of the mixture. Acidic substances which may be usedfor this purpose are oxalic acid, tartaric acid, adipic acid, '5

benzoic acid, cinnamic acid, isocinnamlc acid, uric acid, maleic acid,oxamic acid, pimelic acid, phthalic acid, phthalic anhydride, salicylicacid, tannic acid, tolulc acid, and the like. The lunctioning of theacid or mixture of acids in the mixture is round to depend upon thepolarity, solubility, and neutral equivalent, all of which are closelyrelated as far as this problem is concerned. For example, an exothermicmixture containing benzoic acid, which is an acid of lower watersolubility, higher neutral equivalent and lower polarity than tartaricacid, will require longer to attain the boiling temperature of waterthan one containing the latter acid in the same proportion.

The above indicates the nature and specific embodiments of the essentialingredients in the composition. Others may be added to control theevolution of heat, increase the shell life of the finished product, foreconomy, or for some other reason.

Certain oxides lilre cuprous and cupric oxides appear to be valubleaddition agents because they accelerate the evolution of heat, evidentlyby means by replacement reactions. Such oxides are, however,notessential components.

An additional function or such elements. is to stabilize the mixturebecause they are relatively inert when subjected to atmospheric moistureonly, although becoming active when combining with the acidic mediaproduced by the addition of a substantial quantity of water to themixture.

The addition of a small proportion oi mineral oil is beneficial inretarding the speed of chemical action when the boiling temperature oiwater is reached, and in increasing protection from atmosphericdeterioration. The oil appears to lorm a thin protective illm over thegradients, thereby slowing down the evolution oi water vapor. Theso-called drying oils such as linseed and China-wood oils are veryeflectlve, and in addition they aid the stability 01 the cornpomtionprobably by the removal of tree oxygen from the atmosphere and occludedon the surrace 01 they active ingredients.

Certain desiccatlnz agents, such as calcium sullate or magnesiumcarbonate, may be added to preserve the dryness oi the packaged mixture.This is also aided by preliminary oven-drying o! the mixture bdorcpackins.

As a diluent tor the active ingredients, to aid in protecting the activeingredients from the deleterious eiiects .31 the atmosphere, to reducethe cost of the composition. and to aid in securin: the proper quantity01 heat irom-each pad, we may use pumice, kaolin, kiesclguhr, silica,chalk, calcium sulfate, gypsum, or any other cheap chemically inertmaterial.

Tho iollowinu is an.examplc o! a composition which we and to besatisfactory:

Grams Pumice 6.0 Kaolin 4.0 Aluminum 3.0 Brass 2.0 Potassium chlorate1.5-, Ouprous oxide 0.2 Cuprcos chlor 0.6 Linseed nfl 0.2 Magnesiumcarbonate 0.1 Itwillboporooivcdthot the mop rtionsottho ina'edicnts maybe quite widely varied to obtain variousshspcsotcoolinscurves.Anexplanation olthe chemical reactions whitahcplacewhcnsuchamixtureismoistonodwith m is ted by the simuloccursurtace of the inrence of several reactions and by the intcrdepend-Ou2Ch 23 0 --o 0:1,(013), 280i Ouprous water on rous hydrochloricchloride by side acid $011.10]; 2A1 -0 2Al0ll OOn Curpous aluminumaluminum copper chloride chloride BOT H Cl- Hydrochloric hydroesnchlorine ions "sold ions H K0101 H010; K Hydrogen potassium chloripotassium ion s chlorate acid ions AlOh 33.0 AKOH); and] Aluminum wateraluminum hydrochloric chl0rld0 hydroxide add Cmo 21101 CusCls H1OOuprous hydrochloric cu rous water oxide Orido 3301 Al AlOh 3HHydrochloric aluminum aluminum hydrous acid 4 chloride 23010, E10 201Ohlorlc sold water chlorine omen 0 par 0 a cup 0 p chloride as 201 ---t21101; Zinc chlorine sins chloride .u 301 ------o' AlOh Aluminumchlorine 4 um chloride ZnOh 21110 --v Zngflh 2K0] zinc chloride m ohydrochloric hydroxide acid ovoil mg 0535). .mm

o s o ydrochlorio nd: hy oxi e odd SZnOh RAl' 2Al01; I m Zinc chloridealuminum aluminum Zine chlorido 26inch m M nich son. uprlo nmi-n nmlnnmcopper chloride chloride nu o --o m0 Hydrogen own new Undoubtedly otherequations expressing possible reactions could be written, although theabove are sumclent to account for the behavior or the composition whenmoistened. It will be seen that the malority of them enrollsoxidationreduction or t reactions, both of which are known to be hiahlyexothermic.

Itwillbeunderstoodthattheexampleoia satisfactory composition upon whichthe torngoin: equations are based suucsts quantities which may be variedsubstantially in some instances without noticeable choose in resultsand.

in other instances with chances which may be considered advantageousaccordin: to the degrees of heat produced and the timopsriodsovcr whichproduction or hcatis extend As suucstivsot suchvariationsin quantities,itlsnotcd that the inortdllwsntmayvaryi'rombtommms, aluminum from i to 0grams. the brass mobmllmmathepotassiumchlontetrommitobmmathccuprousoxideirommwtoe mmathocuprouschloridetrom02to4uams.Aspreviously indicated. the mincrlloilandmsancsium temaybeclimlnntedentirely usedlnquantitiesasstatedorsubstmtiallylsner according to themass of the other ingredients involved.

As an example of an exothermic mix utilizing organic acid as a source ofthe acidic media, the

following has proved satisfactory, although neither the specificingredients named nor the proportions given need be adhered to in viewthe earlier references to equivalents:

' Grams Brass 2 0 Pumice 6 0 Kaolin 4 0 Aluminum 3.3 Cuprous oxide 0.Salicylic acid 0.8 Raw China-wood oil 0.1 Potassium chlorate 2.4Magnesium carbonate 0.1 The above mixture when moistened with water,produces substantially simultaneously a number of reactions, many ofwhich are interdependent upon each other. The most essential, althoughnot necessarily all of the resulting actions, may be summarized by thefollowing equations, the majority of which express oxidation-reductionor displacement reactions, both of which are known to be highlyexothermic:

I OH on Gi H +CaH1\ COOH 000- Balicyllc acid hydrogen saiicylate ion (insolution) ions 11+ X010} -9 H010, Kt Hydrogen ion potassium chloric acidpotassium chlorate ion 211010, E10 2C l so Ohloric acid water chlorineoxygen Al 301 --i A191, Aluminum chlorine alummum chloride Cu 201 cuoi,Copper chlorine cupric chloride 2 201 -t 21101, Zific chlorine zincchloride AlCh I'iHaO AKOH): 3HC1 Aluminum water aluminum hydrochloricchloride hydroxide acid cmo 2H0] Gulch H10 Cuprous hydrochloric cuprouswater oxide acid chloride a1 3301 -i x1c11 an Aluminum hydrochloricalumunim hydrogen acid chloride 2A1 search 2x101. 60c Aluminum cuprousaluminum copper chloride chloride 201 01110]! --i fICuCl; Chlorine ontons cupric c orido chloride 213,0 011,01. oul(0H 2301 Water on tons onrent hydrochloric oh orido hy roxide acid ouch 21110 cumin. 21101 Cupriowater cupric hydrochloric hlo ide hydroxide acid 01, 2A1 ---i 2x101. 3CuCupric aluminum aluminum 0 chloride chloride It is obvious that numerouscombinations of ingredients mentioned could be selected from the datagiven herein and the quantities varied to give different results as toextent and degree of heating. All such compositions are considered asembodying the present invention when they are characterized by thepresence of a metal and by the production of hydrogen or hydrogen ionsor hydrochloric acid by the addition or water to an otherwise inertmass, to combine with an oxidizing agent and a substance which in anacidic media will furnish metallic ions replaceable by said metal. Themixtures may comprise two metals of higher and lower electrolyticactivity, respectively, and a source of acidic media of lowerelectrolytic activity than the metal having the hlgher electrodepotential, or the mixture may include but a single metal and the acidicmedia may be supplied by an aqueous solution or an organic acid;

Numerous examples oi such modifications are indicated by the variationsreferred to in the second paragraph following the equations based uponthe first ,iormula given herein and by the reference to similarvariations relative to the second formula. The exclusive use of theseand other modifications of the invention as described in theaccompanying claims s contemplated:

What is claimed is: v

1. A composition for producing heat by chemical action, comprising amixture of a primary metal and a secondary metal, said primary metalbeing from the group or stable metals positioned above the secondarymetal in the electromotive series of metals,-said secondary metal beingfrom the group of stable metals no more active than zinc and activealloys thereof, a substance stable in a dry state and capable when insolution of furnishing an acidic medium, and an oxidizing agentsufiiciently active in the acidic medium and in quantity sufiicient tooxidize both said primary and said secondary metal.

i 2. A composition as described in claim 1 in which the primary metal isselected from' the group consisting of magnesium, aluminum, manganese,cadmium, zinc and active alloys of the same. 1

3. A composition as described in claim 1 in which the secondary metal isselected from the group consisting of zinc, copper, tin, bismuth,antimony, lead, mercury, arsenic, and active alloys of the same.

4. A composition as described in claim 1 in which the primary metal isselected from the group consisting of magnesium, aluminum, manganese,cadmium, zinc, and active alloys of the same, and the secondary metal isselected from the group consisting of zinc, copper, tin, bismuth,antimony, lead, mercury, arsenic, and active alloys of the same.

5. A composition as described in claim 1 in which the substancefurnishing the acidic medium is selected from the group consisting ofcupric sulfate, cupric nitrate, cuprous chloride, cupric iormate, cuprictartrate, cupric lactate, cupric salicylate, cupric sulfite, cupricphosphate; cupric acetate, cuprous bromide, cuprous sulflte, cuprousiodide, cuprous ammonium iodide, and the corresponding salts of iron,cobalt, nickel, bismuth, mercury, tin and lead, oxalic acid, tartaricacid, adiplc acid, benzoic acid, oirmamic acid, isocinnamic acid, uricacid, maleic acid, oxamic acid, pimelic acid, phthalic acid, phthaiicanhydride, salicylic .acid, tannic acid. and toluic acid.

6. A composition as described in claim 1 in which the oxidizing agent isselected from the group consisting of potassium chlorate, ammoniumpersuliatc, sodium perborate and peroxide.

7. A composition as described in claim '1 which includes an additionalingredient insoluble in water and normally inert under atmosphericcondltions and stabilizing the mixture but being ren-.

' o secondary metsl, said primary metal being from a group of stablemetals positioned above the secondary. metal in the electromotive seriesof metals, said secondary metal being from the group of stable metals nomore active than zinc andsctive 'ulioys thereoi. an acidic salt of ametal of lower electrolytic activity than the first of said metals,

and an oxidizing agent sumciently active in the acidic medium and inquantity suilicient to oxidiz'e both said primary metal and saidsecondary metal and reacting more readily with said primary metal thanwith the secondary metal.

9. An exothermic mixture comprising a substantial quantity oi. each of aprimary metal and a. secondary metal, said-primary metal beins from agroup 0! stable metals pomtioned above the. secondary metal in theelectromotive series of metals, said secondary metal being from thegroup oi stsble metals no more active than zinc and active 1 0.85thereof, an acidic salt of a metal of lower electrolytic activity thanthe first 0! said metals, and an oxidizing agent selected irom the groupof potassium chloratmsmmonium persulfate, sodium perborste and bariumperoxide.

10. An exothermic mixture including an inert diluent, aluminum,potassium chlorate, cuprous chloride, and brass.

amass? 11-. An exothermic mixture including the following ingredients inthe proportion indicated- Grams Inert diluent "approximately" 5 to 20Aluminum do ..1 to 6 Potassium chlorate do..- ,0:( to 5 Cuprous chloridedo 0.2 to 4 Bruits "do..-" 0.05 to 5 12. [in exothermic mixtureincluding an inert diluent, aluminum, potassium chlorate, cuprous'chloride, brass, and cuprous oxide.

13. An exothermic mixture including the X01- lowing ingredients in theproportion indicated- 14. An exothermic mixture comprising an inertdiluent. aluminum. brass. potassium chlorate, cu-

prous oxide, cuprous chloride, linseed oil, and

magnesium carbonate.

15. An exothermic mixture comprising an inert diluent, approximately 10parts by weight; aluminum. approximately 3 parts; brass. approximstely 2parts; potassimn chlorate. approximately 1.5 parts; cuprous oxide,approximately-0.2 part7 cuprous chloride, approximately 0.6 part;minersl oil, approximately 02 part; and magnesium carbonate,approximately 0.2 part. i 16. An exothermic mixture comprising an inertdiluent, aluminum, brass, potassium chlorate, salicylic acid. cuprouschloride, drying oil, and magnesium carbonate.

mnmmn RACEN. WALTER M. BRUNER.

